Complete Care for Your Aging Cat - Amy Shojai [83]
Surgery
Surgery is the most common cancer therapy for pets. “Surgery is sort of a two-edged sword,” says Dr. Ehrhart. “It has the potential to cure more cancer than any other therapy that we used, especially single-modes of therapy. But at the same time, if it’s used improperly it has the potential to harm you.” She strongly urges owners to seek the advice of a cancer specialist before beginning treatment.
Tumors can be removed with advanced techniques such as lasers and noninvasive arthroscopic technology. Cancer is nearly impossible to cure using surgery alone, though. Surgery often disturbs and may distribute cancer cells to other locations. Also, leaving behind even a single cancer cell could allow the tumor to return. In most situations where surgery is used, it is followed by chemotherapy, radiation, or other therapies.
Radiation
Surgery isn’t the best choice when a tumor is near vital organs or nerves that also may be damaged, or on the face, where little extra tissue is available. For these tumors, radiation therapy often is used.
Intense X-rays are shot into the malignancy to kill the cells. Conventional beam radiation can’t tell the difference between the cancer and normal tissue, and can cause damage these areas as well. Human cancers treated with radiation therapy tend to be near other sensitive tissues such as the lungs or intestines. That’s why human cancer patients treated with radiation often suffer severe side effects, such as nausea and hair loss. These side effects are rare in cats because the pet’s tumors typically are on the head or neck, far from sensitive organs. Occasionally cats temporarily lose their appetite or shed whiskers. Radiation cures up to 80 percent of some kinds of cancers. It works extremely well on skin and bone marrow cancers.
A concern with radiation is that cats must be anesthetized so the X-ray to be aimed to the right target. Repeated treatments are necessary—often twice a week for six to eight weeks—so repeatedly giving anesthetic to senior cats is a potential problem. New kinds of linear accelerators (radiation machines) have been designed to better target the tumor while sparing normal tissue. They may incorporate CT scanners to help “see” the tumor in three dimensions and better plan the treatment, such as the ones available at Washington State University and Tufts University.
University of Florida veterinarians and scientists created a stereotactic radiosurgery technique using a specially designed medical linear accelerator in conjunction with a three-dimensional ultrasound guidance system. This treatment can pinpoint radiation beams at tumors and avoid damaging normal tissue. Instead of the conventional repeated therapy, it uses a one-time extremely high radiation dose instead of repeated sessions over a period of weeks. That means cats only need anesthesia one time rather than several. It costs roughly the same amount as traditional veterinary radiation therapy.
Chemotherapy
Chemotherapy drugs are designed to poison cancer cells that have spread throughout the body. Chemotherapeutics may be administered as pills, or injected intravenously. They are often used after surgery to kill any stray cells left behind.
Most chemotherapy drugs come from the human arsenal. There’s no standard treatment for a given cancer, says Dr. Kitchell, and different oncologists may have their own favorites. Drugs may be used alone or in combinations, and prices range from expensive to very reasonable.
Since chemotherapy drugs are usually dosed by the animal’s weight, the small size of the cat makes this form of treatment pretty economical. But if the first drug you try doesn’t work, it’s not the end of the world. “Chemotherapy is not like jumping off a cliff,” says Dr. Ehrhart. “You can do a reduced dose the next time or change drugs.